Side scrapers of the type with which this invention is involved overlie the inclined surface of an elongate heap of loose material and are movable transversely of a heap for the purpose of discharge of loose material from the heap by taking down the heap from its top surface. The material is discharged from the top of the heap to the foot of the heap as the scraper scoops are lowered into the surface of the heap to a specific depth and convey the loose material from the top of the heap to the bottom and at the same time the scraper arm is moved in the longitudinal direction of the heap.
In order that the scraper scoops can always be lowered into the surface of the heap to a specific depth as the discharge of material progresses, the scraper arm is pivotable in the region of the foot of the heap about an axis which runs parallel to the longitudinal direction of the heap. This results in the cutting depth of the scraper scoops being greatest at the top of the heap and zero at the bottom. Thus the cleared loose material has a cross-sectional profile of an elongated triangle. As a result certain problems relating to the discharge of loose material occur in the lower region of the scraper arm.
In the upper region of the heap, where the scraper scoops penetrate relatively deep into the loose material, a high material bed into which the scraper scoops cut is located on the side of the scraper arm which faces in the direction of movement (based upon the movement of the scraper arm in the longitudinal direction of the heap). This material bed forms the support for the scraper scoops which is necessary so that within the scraper scoops the loose material taken up by the scoops moves in the transverse direction of the scoops from the outer side which is to the fore when viewed in the direction of movement (in the longitudinal direction of the heap) to the opposite side.
On the other hand the situation in the lower region of the heap of loose material is different. Because the scraper scoops here dig less deeply into the surface of the heap, the support which is necessary for the crosstransport of the loose material in the scoop builds up in the form of a mound or ridge of loose material on the cutting side of the scraper scoops (i.e. on the outer side of the scraper arm which is to the fore in the longitudinal direction of the heap). The dimensions of this mound of loose material are proportional to the discharge capacity. The specific gravity of the loose material has an influence. The lower the density of the loose material is, the greater are the dimensions of the mound of material.
The considerable friction which occurs between this essentially stationary mound of material and the revolving scraper conveyor leads to a considerable energy loss and severe wear on the moving parts of the side scraper.